Nithiazine, 2-nitromethylene-tetrahydro-2H-1,3-thiazine is an active ingredient in a number of insecticidal compositions. It has been described as having activity against rice insects including both moths and flies. However, nithiazine is a relatively unstable compound which will decompose under thermal, sunlight, or moisture conditions.
A number of approaches have been investigated in an effort to stabilize nithiazine formulations. Japan patent JP 57002208 reports the stabilization of nithiazine using .alpha.- and .beta.- naphthols or phenols having two to three hydroxy radicals attached to the benzene ring. In Japan patent JP 5718604, nithiazine is stabilized with potassium salts of carboxylic acids or phosphoric acids. Japan patent JP 5718605 describes the stabilization of nithiazine with urea or thiourea. More recently, JP 59134703 described the use of secondary aromatic amines such as N-methylaniline, N-methyltoluidine, diphenylamine and N-phenyl-.beta.naphthylamine to prevent decomposition of nithiazine.
Despite the above approaches, there exists a need for compositions which provide a long-term stabilization of nithiazine to both thermal and UV conditions. Surprisingly, the present invention provides such compositions.